Wide angle eyepiece



July 2. 1968 TU 3 L i uuuwfl RUU MHz/T w w. H. SCIDMORE 3,390,935

' WIDE ANGLE EYEPIECE Filed April 9, 1965 SDWOMM WRIGHT H. SOIDMORE United States Patent Office 3,390,935 WIDE ANGLE EYEPIECE Wright H. Scidmore, Langhorne, Pa., assignor to the United States of America as represented by the Secre- 3,390,935 Patented July 2, 1968 TABLE I.OPTICAL LEGEND L the individual lens r-the radius of curvature d-axial thickness of lens tary of the Army 5 Filed Apr. 9, 1965, Ser. No. 447,112 1? d 1 Claim. 01. 350-206) we ex V--Abbe number of the glass Ftotal focal length of the eyepiece f and -focal length of cemented doblet, L1-L2 ABSTRACT OF THE DISCLOSURE l fa foscal length of lens L3 A wide angle eyepiece having an apparent field of view f focal length of lens L; of about 80, said eyepiece comprising, from the objecf and f0cal length of cemented doublet, L5-L5 tive to the eyepiece; a diaphragm, a cemented doublet C.A.-Clear aperture TABLE II.LENS TABLE DATA Ele- Radii Axial Air Space 11,] V C.A. ,7 ment Thicknesses Thicknesses D .1 n =oo C.A. =l.568

l, =.326 =-1.s75 ca. =1.446

d =-.133 m =1.649 V, =33.s L1, L1. T] =+L875 d1 =.639 7Z1 =1-620 V: =60.3 r4 =l,875 ca, =1.792

l, =.009 T5 =+4.766 L: n d: =.337 723 =1-620 V; =60-3 (1A,; =1.858

l1 =.009 r1 =+1.s75 L4 d4 =.399 m =l.620 V4 =60.3 C.A.( =l.758

l4 =.009 r =-+1.346 0A., =1.436

d5 =.46l 7L5 =L620 V =60.3 L5, L5. ho =-2.018

a, =.107 m =l.649 vi =33.8 r =+2.808 C.A.t =1.o01

Equivalent focal length, F=1.000, fl and 2=39.9F,fi=3.90F,]1=3.02F,/5 and s=3.93F.

field lens, two singlet center lenses and a cemented doublet eyelens.

The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to eyepieces and more particularly concerns such optical devices providing an apparent field coverage in the neighborhood of 80 or so and having good correction qualities over the entire field.

The principal object of the invention is to provide eyepieces as aforementioned.

Another object of the invention is to provide eyepieces wherein the number of different lens radii is held to an absolute minimum thereby simplifying manufacturing procedures and lowering production costs.

The exact nature of this invention as well as other objects and advantages thereof will be readily apparent from consideration of the following specification and single figure of the drawing which illustrates a diagrammatic embodiment of my inventive device in axial section.

Briefly, the present invention is based on the discovery that by judiciously axially disposing optical components, an efficient, compact, wide angle" eyepiece is provided possessing good correction qualities over its entire field of view.

More specifically, my present invention resides in a wide angle eyepiece commonly known as the 2-1-1-2 type and, from front to rear, or from the objective to the eyepiece, consists of a diaphragm, a cemented doublet field lens, two singlet center lenses and a cemented doublet eyelens.

Referring now to the drawing, a diphragm D functions as a field stop to aid in limiting the apparent field of view of my device to a desirably wide angle of about Approaching eye E from diaphragm D is a field lens consisting of an equi-concave lens L cemented to an equi-convex lens L such that r =r =r The focal length of this field lens L and L is approximately 399 F. Proceeding still rearwardly, or toward the eye E, an equi-convex singlet center lens L where r =r has a focal length of about 3.90 F. Adjacent thereto is a convexplano singlet center lens L.,,, where r',=r =r =r its focal length approximating 3.02 F. The optical component nearest the eye E is a cemented doublet consisting of bi-convex lens L cemented to a bi-concave lens L Positive radius r; of the lens L is about 0.667 times that of a negative radius r and 0.479 times smaller than r Cemented doublet L L has a focal length in the neighborhood of about 3.93 F.

Positive refracting power lenses L L L and L are made conveniently of 620/603 glass whereas negative lenses L and L, can be ground from 649/338 glass.

The Petzval curvature or sum my eyepiece is 0.492 F, the Petzval radius being 2.033 F.

I claim:

1. A wide angle eyepiece comprising, axially from front to rear,

a diaphragm function as a field stop to aid in limiting apparent field of view to about 80,

a cemented doublet field lens,

a pair of singlet center lenses and,

a cemented doublet eyelens,

said eyepiece conforming substantially to the following table in which dimensions are in terms of inches and proceeding from front to rear, D represents said diaphragm, L to L, deisgnates the lens of said eyedispersion numbers of said respective lenses and piece, r to r design-ates the radu of curvature of C.A. to C.A. designates the clear apertures of the surfaces of said diaphragm and the respective lenses, respective lenses and C.A. designates the clear the number of different I'adll for the entire eyepiece aperture of said diaphragm,

Ele- Radli Axial Air Space m V C.A. ment Thlcknesses Thicknesses D r =oc C.A.D=1.568

z, =.326 T3 =1.875 C.A.1 =14;

d =.133 n =1.649 V =3a.s L1, 142.. r; =+1.875

d =.639 714 =l.6m V1 =60.3 (4 =1.875 C.A.z =1.792

l3 =.009 r, =+4.766 L; d; =.337 n =1.e20 v, =s0.3 0A.; =1.s5s

I; =.009 r1 =+1.s75 Lt d4 =.399 m =1.620 v. =60.3 0A.. =1.75s

l4 =.009 n =+1.s4e 0A.; =1.436

d5 =.461 7Z5 =1.620 V =60-3 L5, L5. r 0 =2.018

d, =.107 m =1.64s V =33s m =+2.sos 0A.. =1.001

Equivalent focal length, F=1.000", It "a :=39.9F,f;=3.90F,f4=3.02F, f; "a o=3.93F.

being only eight, d to d, designates the axial thicknesses of said respective lenses, l to designates the No references cited. axial air space thicknesses between respective ele- 30 ments, n; to n, designates the indices of refraction JOHN CORBIN, Primary Examinerof said respective lenses, V to V designates the Abbe 

